iOS 18 was a odd ball, so going to look back to before this release.
iOS 17 - had 3 betas and 2 RCs (public Weds Oct 25th)
iOS 16 - had 5 beta and 1 RC (public Mon Oct 24th)
iOS 15 - had 4 betas and 2 RCs (public Mon Oct 25th)
So assuming 4 or 5 betas and or RC, we could be looking at the following:
Sept 22nd week beta 1 was released.
Oct 6th week - potentially beta 2
Oct 13th week - potentially beta 3
Oct 20th week - RC (maybe beta 4)
Oct 27th week - potentially public release
Tomorrow to me will be the telling sign. It could be the first time in a while we get a 1 PM Eastern Dev / 4 PM Eastern Public. If we don't get something tomorrow, I think we align to the schedule above.